J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Airmar DST 800

The retractable Airmar DST800 is not reading true speed. There is approximately 50% variance between the GPS and Tacktick displays. Too much of a difference to be accounted for currents. It worked fine until I removed it for cleaning. I suspect it is not going in all the way when reinserted resulting in the paddle wheel not getting the full benefit of the flow. Has anyone had a similar experience with retractable transducers?

Try pulling it again and make sure that the paddlewheel is centered in the slot. If it rubs against the side, it could give an error. You can use a drift pin to push out the paddlewheel pin and clean everything up, then reassemble. Make sure the cups face the right direction on reassembly.

I pull the paddlewheel and put in the blanking plug whenever the boat is tied up, so never need to worry about cleaning the paddlewheel.